pragma solidity ^0.4.23;

// ================= Ownable Contract start =============================
/*
 * Ownable
 *
 * Base contract with an owner.
 * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
 */
contract Ownable {
  address public owner;

  constructor() public {
    owner = msg.sender;
  }

  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  function transferOwnership(address newOwner) public onlyOwner {
    if (newOwner != address(0)) {
      owner = newOwner;
    }
  }
}
// ================= Ownable Contract end ===============================

// ================= Safemath Lib ============================
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  /**
  * @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}
// ================= Safemath Lib end ==============================

// ================= ERC20 Token Contract start =========================
/*
 * ERC20 interface
 * see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  function burn(uint256 _value) public returns (bool);

  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  
  // This notifies clients about the amount burnt
  event Burn(address indexed from, uint256 value);
}
// ================= ERC20 Token Contract end ===========================

// ================= Standard Token Contract start ======================
contract StandardToken is ERC20 {
  using SafeMath for uint256;

  mapping(address => uint256) balances;
  mapping (address => mapping (address => uint256)) internal allowed;

  uint256 totalSupply_;

  /**
  * @dev total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
  }


  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }


    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
  function burn(uint256 _value) public returns (bool success) {
      require(balances[msg.sender] >= _value);   // Check if the sender has enough
      balances[msg.sender] -= _value;            // Subtract from the sender
      totalSupply_ -= _value;                      // Updates totalSupply
      emit Burn(msg.sender, _value);
      return true;
  }
  
}
// ================= Standard Token Contract end ========================

// ================= Pausable Token Contract start ======================
/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;


  /**
  * @dev modifier to allow actions only when the contract IS paused
  */
  modifier whenNotPaused() {
    require (!paused);
    _;
  }

  /**
  * @dev modifier to allow actions only when the contract IS NOT paused
  */
  modifier whenPaused {
    require (paused) ;
    _;
  }

  /**
  * @dev called by the owner to pause, triggers stopped state
  */
  function pause() public onlyOwner whenNotPaused returns (bool) {
    paused = true;
    emit Pause();
    return true;
  }

  /**
  * @dev called by the owner to unpause, returns to normal state
  */
  function unpause() public onlyOwner whenPaused returns (bool) {
    paused = false;
    emit Unpause();
    return true;
  }
}
// ================= Pausable Token Contract end ========================

// ================= RVTCoin  start =======================
contract RVTCoin is StandardToken, Pausable {
  string public constant name = 'Renvale Token';
  string public constant symbol = 'RVT';
  uint256 public constant decimals = 18;
  address public rvDepositAddress; 

  uint256 public constant rvDeposit = 2000000000 * 10**decimals;

  constructor(address _rvDepositAddress) public { 
    rvDepositAddress = _rvDepositAddress;

    balances[rvDepositAddress] = rvDeposit;
    emit Transfer(0x0, rvDepositAddress, rvDeposit);
    totalSupply_ = rvDeposit;
  }

  function transfer(address _to, uint256 _value) public whenNotPaused returns (bool success) {
    return super.transfer(_to,_value);
  }

  function approve(address _spender, uint256 _value) public whenNotPaused returns (bool success) {
    return super.approve(_spender, _value);
  }

  function balanceOf(address _owner) public view returns (uint256 balance) {
    return super.balanceOf(_owner);
  }

  function burn(uint256 _value) public returns (bool success){
     return super.burn(_value);
  }
}
// ================= Token Contract end =======================